Being in the UK our prices are usually higher than yours anyway. But over here i don't think Tamiya is to bad. I just compared Fw 190 kits, and the tamiya ones are more than say Acedamy and revell, around £10 for the Tam and around the fiver mark for the other two, they are still cheaper than the AZ model kits, and i have no idea what they are like.
As for the Mossie, i think you guys are being ripped off i found two Tamiya 1/48th kits for £22, which is about $30-£35.